Lock joint for artificial hands



D. w. DORRANCE LOCK JOINT FOR ARTIFICIAL HANDS Feb. 23, 1932.

Filed May 22, 1930 2 SheetsSheet 1 gwumhw D. WDorrun Feb. 23, 1932.

D. w. DORRANCE LOCK JOINT FOR ARTIFICIAL mamas Filed May 22, 1930 2 Sheets-Sheet 2 gwumtw llwfparrance,

Patented Feb. 23, 1932 Q mv-ID-w. nonsense, or, SAN :iosii, CALiFOBNiA' LOCK JOINTIFOR nnriri cmtnnnns V pplication filed May-.22,

:The object of the invention is to provide an artificial hand comprising complemental fingers which are positivelylocked against furth'er openingmovement than that to which they are adjusted as when they are caused to grip on a tool ortoengage the handle of some device to be carried; to. provide a lock of this naturewhich will function withthe movement of the fingers in the infinitesimal incre-' ments; to provide for the automatic release of the lock bythenieans-eifecting the norillustrated in.

'- from a direction at right angles fromthat' locking means may mal opening movement or operation ofthe fingersyto provide means for manual operationby which the release or setting of the be accomplished independently' of the means provided for the au tomatic functioning of this feature; to pro-* vide aconstructionwhiohwill make for the free relative swinging movement of the fingers; and to provide a construction of-the character describedwhich is generally of simple form and susceptible of comparatively 'cheap'manufacture' and low marketing cost.

object in view the invention con- *With-this A v sists in a construct on and combination-of parts of which a preferred embodimentis the accompanying drawings,

wherein: w r

Figure 1 is aside elevational view of an artificial hand embodying the invention.

Figure 2' is an elevational view looking from whichjFigure 1 is viewed; 1

' Figure 3 is a viewasi nilar to'Figure 1 but looking at the reverse sideofthe latter.

, Figure l is a view on an enlarged scale and partly in section, and'illustrating the lock comprised in the invention, the parts being. illustrated in the positions assumed whenthe fingersare in closed position: I e Figure 5 is a view similar to Figure 4 L, the fingers being shown in partial, open position. Figure 6 is a viewsiinilar to Figure 4: with the full open position of the fingers being indicated. 7

Figure Tis a perspective View, illustrating the rock shaft constituting the locking element. V

Figure 8 is a detail perspective view 'illus-- 19:30. Serial iiofisesiv.

oted fingers. V .1 p

Figure9 is-a detail sectionalview on the trating the eye and adjacent parts of the pivplane indicated by the line 9- 9 ofnFigure 2. V

The fingers 10; and: 11 are connected 'for relative 'movement, the former being formed witha -base or bodyfportion 12 whichatits 10, being carriedin grooves formed. in the v two which provide. a. ball race, so that the balls inay provide for ready swinging movement ofthe finger: 11 with reference to the fingerilOn v. .1. r

Rotatably mounted in the body portion 12 with its axis parallel to the axis of the screw 15is .arock shaft 19, this rock shaftbeing reduced between its 'endsas indicated at 20 ,to provide. an eccentric portion which is moved toward or. away from the periphery of'the eye portion 17, whenthe rock shaft' is rotated. A 'sectionof the periphery' of the eye portion 17, as indicated at 21,is shaped to a curve of gradually reduced radius forming cam and as the pivotedefinger 11 is 'nioved fronrclosed to open position; the cam traverses the eccentric portion 20 from the lowest point of the former to thehig'hest,

. if the position ofthe eccentric portion is such as to p'ermit free passage of the cam;

Therock shaft 19, atone end, is formed 2 with the spaced flanges 22 andzinthe space between these flanges is received the coil spring 23wvhioh is terminallyc'onnected to the shaft by means of its inturned extremity 24 engaging a diametrical hole 25 in the shaft, the remainingiterminal of'the spring "being anchored to the body portion 12 by means of the screw 26, The tendency of the spring. is to rotate the rock shaft so as to dispose the eccentric portion against the cam 21 and whatever the relative positions of the two fingers and 11, anytendency to shift the pivoted finger 11 to further open position by a force applied'to the finger, results in a tendency to rotate the rock shaft by .the

pressure of the camrupon the-eccentricpontion 21 and this against the turning force of the spring. Since the turning force applied to the rock shaft under such conditions is-almost directly radial, the eccentric portion acts as a positive lock vto the pivoted finger 11 against further opening movement..- Thus if the fingers be separated and closed upon an interposed object, practically no force ap plied by that object tending to effect further open position will result in further separation ofthefingers.

The fingers are normally yieldingly' impelledlt'owards closed position by the mem-,

bers:.27 which are preferably elastic bands "togtheilatter by-a fastener'36. That end of v, the arm 34-remote fromthegfastener 36 constitutesasingle manipulating terminal 37 by means ofiwhich theirock shaft maybe 'actuated independently of the means normally provided for its actuation and the separation of thefingerslO and 11. 1 Y In the use of the invention, the user is provided vwith a harness for attachment to the-body. at some point withi-a pull cord exi tending preferably through the-sleeve and terminally connected w-ith'the' eye 32; By this =means heimay exert a pull'on th'epull 'cord which then rocks the lever 31 which in turn rocks the-rock shaft 19 through the instrumentality of the link 33 and arm 34, thus swinging the eccentric portion 20 away from th'ezcam 21, the'continued Epull then resulting in "swinging the finger 11 away from the fin .ger 1O for'theplacement ofan object or tool to be inserted therebetween.

and 11 are engaged with theinterp'osedob- 'jectxand, since thespring 23 has restored the normal position of the roclt shaft, its eccen triciportion 20 is in obstructing. relation to the'cam 21, and backward swinging or opening movement of the finger 11 is precluded."

, The rock-sl1aft actuating terminal '37 is provided Ffor rocking the rock shaft in the same manner: as would be accomplished 7 On release 'of the pull on'theipul'l cord, the two fingers 10 through the link 33, but only in case of any sticking or binding between the cam and ec-' centric portion 20. Conversely, 23 failing to shift the eccentric back into engagement with the cam after having once been separated therefrom, pres sure on the terminal 35 suffice to accomplish this; V k

The invention having been described What is claimed as new and useful is the spring 1-5 Ania-rtificial hand comprising pivotally connectedifingers yieldingly impelled t0- "wards'eaichother; and a rocking device carfrie d by. the one 7 and engageable with the other, said rocking device comprising a rock shaft" having an-iec-centr'ic portion, the finger engaged thereby having. a cam contacting 'with 'said eccentric portion, and a spring tendingxto rotate the rock shaft to movethe eccentric portiontowards said cam.

- 2. Anartificial hand comprising pivotally portion 20 (,Of the arm 34 will i 'conne1cted"fingers yieldingl-y impelled to I wardseach other, andh a rockingdevice carried by the one an'd'engageabl-e With the :ot'h'ensaid rocking device comprising arock shaft'having an eccentric portion, the finger engaged thereby having a'camcontacting with saideccentric portion, and a spring tendingito rotate the rock shaft to move the eccentric portion towards; said cam, the cam i carrying finger having means. for attachm'ent to' apull cord and-operative connections between said means-and the rock sha ft to effect rotation of the latter in opposition to said spring. and an advance ofapplying a pull on'sa'idfingen' V K 3. Ana artificial hand comprising pivotally connected fingersy ieldinglyimpelled to wards each other, and 'a'ro'cking device carried-by the onean'dengageab'le with the other,

said rockingidevice comprising a rock shaft h'avin gz an eccentric portion, the finger en gaged thereby having a cam contacting with said eccentric portion, and a spring tending to rotate the'rock shaftto move the eccentric portion towards said cam, the cam carrying lin ger having means for attachment'to a pull cord and operative connections between said means and the rockshaft to effect rotatlon of the latter in opposition to said spring and injadvance ofvapplyinga pull on said fin- .ger, thepull cord attaching means consisting of a :le'verpivotally mounted on said finger and "said "operative connection. comprising an arm 'carri'edby the'ro'ck'shaft and a link pivotally connectin'g' said lever and saidarIn;

I 4: artificial hand comprising pivotally "connected fingers yieldingly impelled towards each other, and 'a rocking device carriedby'the oneand-engageable with the other, said rocking device comprising a roek shaft having: an eccentric portion, the finger *en-.

gaged 'tliereby havin'ga oam contacting :with

said eccentric portion, and a spring tending to rotate the rock' shaft to movethe i-eocen'tric portion towards said cam, the cam carrying finger having means for attachment to a pull cord and operative connections between said means and the rock shaft to eifect 10- v 5 tat-ion of the latter in opposition to said spring and in advance of applying a pull on said finger, the pull cord attaching means consisting of a lever pivotally mounted on said finger and said operative Connection 7 10 comprising an arm carried by the rockshaft and a link pivotally connecting said lever and said arm, said arm, beyond the pivotal con i nection with said link being provided with" a single terminal for the independent actuav tion of the rock shaft. v v

'5. An artificial hand comprising pivotally connected fingers yieldingly impelled to-v wards each other, the one being formed with a cam, a rock shaft rotatably mounted in the other and having aneccentric portion engageable with the cam when the rock shaft is rotated in one direction and separated from the cam when the rock shaft is rotated in the opposite direction, a spring tending to rotate the shaft in a direction to engage the cam and eccentric portion of the rock shaft, pull cord actuated means for rotating the rock shaft in a direction opposite to that effected by the spring, said means having an 0 element carried by the cam carrying finger so as to subsequently effect movement of that finger with reference to the other finger..

6. An artificial hand comprising pivotally connected v fingers yieldingly impelled towards each other, the one being formed with a earn, a rock shaft rotatably mounted in the other and having an eccentric portion engageable with the cam when the rock shaft is rotated in one direction and separated from 40 the cam when the rock shaft is rotated in the opposite direction, a spring tending to rotate the shaft in a direction to engage the cam and eccentric portion of the rock shaft, pull cord actuated means for rotating the rock shaft in a direction opposite to that effected by the spring, said means having an element carried by the cam carrying finger so as to subse-o quently effect movement of that finger with r reference to the other finger, and means for manually actuating the rock shaft independ:-. ently of the pull cord means. i

" In testimony whereof he afiixes his sigr nature.

DAVID w. DORRANCE. 

